| 1. |
- Mendez-Hernandez, H., et al.
(author)
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VALES VI: ISM enrichment in star-forming galaxies up to z similar to 0.2 using (CO)-C-12(1-0), (CO)-C-13(1-0), and (CO)-O-18(1-0) line luminosity ratios
- 2020
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In: Monthly Notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 497:3, s. 2771-2785
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Journal article (peer-reviewed)abstract
- We present Atacama Large Millimeter/sub-millimeter Array (ALMA) observations towards 27 low-redshift (0.02< z< 0.2) starforming galaxies taken from the Valpara ' iso ALMA/APEX Line Emission Survey. We perform stacking analyses of the (CO)-C-12(1-0), (CO)-C-13(1-0), and (CO)-O-18(1-0) emission lines to explore the L' [(CO)-C-12(1-0)]/L' [(CO)-C-13(1-0)] [hereafter L' ((CO)-C-12)/L' ((CO)-C-13)] and L' [(CO)-C-13(1-0)]/L' [(CO)-O-18(1-0)] [hereafter L' ((CO)-C-13)/L' ((CO)-O-18)] line luminosity ratio dependence as a function of different global galaxy parameters related to the star formation activity. The sample has far-IR luminosities of 1010.1-11.9 L and stellar masses of 109.8-10.9M(circle dot) corresponding to typical star-forming and starburst galaxies at these redshifts. On average, we find an L' (12CO)/L' ((CO)-C-13) line luminosity ratio value of 16.1 +/- 2.5. Galaxies with pieces of evidence of possible merging activity tend to show higher L' ((CO)-C-12)/L' (13CO) ratios by a factor of 2, while variations of this order are also found in galaxy samples with higher star formation rates (SFRs) or star formation efficiencies (SFEs). We also find an average L' ((CO)-C-13)/L' ((CO)-O-18) line luminosity ratio of 2.5 +/- 0.6, which is in good agreement with those previously reported for starburst galaxies. We find that galaxy samples with high LIR, SFR, and SFE show low L' ((CO)-C-13)/L' ((CO)-O-18) line luminosity ratios with high L' ((CO)-C-12)/L' ((CO)-C-13) line luminosity ratios, suggesting that these trends are produced by selective enrichment of massive stars in young starbursts.
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| 2. |
- Penney,, et al.
(author)
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Cold molecular gas and free-free emission from hot, dust-obscured galaxies at z similar to 3
- 2020
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In: Monthly Notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 496:2, s. 1565-1578
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Journal article (peer-reviewed)abstract
- We report on observations of redshifted CO(1-0) line emission and observed-frame similar to 30 GHz radio continuum emission from five ultra-luminous, mid-IR selected hot, Dust-Obscured Galaxies (Hot DOGs) at z greater than or similar to 3 using the Karl G. Jansky Very Large Array. We detect CO(1-0) line emission in all five Hot DOGs, with one of them at high signal-to-noise ratio. We analyse FIR-radio spectral energy distributions, including dust, free-free, and synchrotron emission for the galaxies. We find that most of the 115 GHz rest-frame continuum is mostly due to synchrotron or free-free emission, with only a potentially small contribution from thermal emission. We see a deficit in the rest-frame 115 GHz continuum emission compared to dusty star-forming galaxies and sub-millimetre galaxies (SMGs) at high redshift, suggesting that Hot DOGs do not have similar cold gas reserves compared with star-forming galaxies. One target, W2305-0039, is detected in the FIRST 1.4 GHz survey, and is likely to possess compact radio jets. We compare to the FIR-radio correlation, and find that at least half of the Hot DOGs in our sample are radio-quiet with respect to normal galaxies. These findings suggest that Hot DOGs have comparably less cold molecular gas than star-forming galaxies at lower, z similar to 2 redshifts, and are dominated by powerful, yet radio-quiet AGN.
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| 3. |
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| 4. |
- Aravena, C., et al.
(author)
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Does money talk? - The effect of a monetary attribute on the marginal values in a choice experiment
- 2014
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In: Energy Economics. - : Elsevier BV. - 0140-9883. ; 44, s. 483-491
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Journal article (peer-reviewed)abstract
- When designing choice experiments for nonmarket valuation the role of the price attribute is of major importance. In the energy sector the uncertainty of future direction of changes in prices makes it difficult to include an adequate price vector in the design. We separately investigate the implication of using price vectors with increases and decreases in tariffs from current levels, on marginal value estimate from choice experiment data developed using prospect theory. In addition, we also analyse the effect of excluding the price vector on these marginal values. By and large, our results support the neoclassical theory as we find that the means of the conditional estimates of the marginal values of attributes are unaffected by the direction of the price change and from exclusion of the price attribute. However, the distributions show a larger spread of values when the choice experiment implies a tariff decrease, which may have policy implications.
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| 5. |
- Hammarlund, Dan, et al.
(author)
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Multi-component carbon isotope evidence of early Holocene environmental change and carbon-flow pathways from a hard-water lake in northern Sweden
- 1997
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In: Journal of Paleolimnology. - 0921-2728. ; 18:3, s. 219-233
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Journal article (peer-reviewed)abstract
- A 9000-year carbonate-rich sediment sequence from a small hard-water lake in northernmost Sweden was studied by means of multi-component stable carbon isotope analysis. Radiocarbon dating of different sediment fractions provides chronologic control and reveals a rather constant hard-water effect through time, suggesting lake has remained hydrologically open throughout the Holocene. Successive depletion of C-13 in fine-grained calcite and carbonate shells during the early Holocene correlate with a change in catchment vegetation from pioneer herb communities to boreal forest. The vegetational change and associated soil development likely gave rise to an increased supply of C-13-depleted carbon dioxide in groundwater recharging the lake. This process is therefore believed to be the main cause of decreasing values of delta(13)C in dissolved inorganic carbon of the lake and thereby in limnic carbonates. Strongly C-13-depleted sedimentary organic matter may be related to enhanced kinetic fractionation during photosynthetic assimilation by means of proton pumping in Characean algae. This interpretation is supported by a substantial offset between delta(13)C of DIC as recorded by mollusc shells and delta(13)C Of fine-grained calcite.
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| 6. |
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| 7. |
- MacDonald, GM, et al.
(author)
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Holocene treeline history and climate change across northern Eurasia
- 2000
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In: Quaternary Research. - : Cambridge University Press (CUP). - 0033-5894 .- 1096-0287. ; 53:3, s. 302-311
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Journal article (peer-reviewed)abstract
- Radiocarbon-dated macrofossils are used to document Holocene treeline history across northern Russia (including Siberia), Boreal forest development in this region commenced by 10,000 yr B.P, Over most of Russia, forest advanced to or near the current arctic coastline between 9000 and 7000 yr B.P. and retreated to its present position by between 4000 and 3000 yr B.P. Forest establishment and retreat was roughly synchronous across most of northern Russia, Treeline advance on the Kola Peninsula, however, appears to have occurred later than in other regions. During the period of maximum forest extension, the mean July temperatures along the northern coastline of Russia may have been 2.5 degrees to 7.0 degrees C warmer than modern. The development of forest and expansion of treeline likely reflects a number of complimentary environmental conditions, including heightened summer insolation, the demise of Eurasian ice sheets, reduced sea-ice cover, greater continentality with eustatically lower sea level, and extreme Arctic penetration of warm North Atlantic waters. The late Holocene retreat of Eurasian treeline coincides with declining summer insolation, cooling arctic waters, and neoglaciation, (C) 2000 University of Washington.
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| 8. |
- Pino, K., et al.
(author)
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Regional landscape change triggered by Andean uplift: The extinction of Sparassodonta (Mammalia, Metatheria) in South America
- 2022
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In: Global and Planetary Change. - : Elsevier BV. - 0921-8181. ; 210
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Journal article (peer-reviewed)abstract
- Sparassodonta, a Metatherian monophyletic group, was the main mammalian carnivore predator clade in South America from the Paleogene to the Early Pliocene (c. 66–3.5 Ma). However, there is still no consensus on the causes of their demise. Here, we use the fossil record and Bayesian diversification models to infer the origination and extinction rates for Sparassodonta. Then, we evaluate if their demise can be attributed to global temperature changes, Andean uplift, biotic interactions with their competitor and prey clades, and body mass evolution. That is biotic aspects in the context of the Red Queen model, abiotic aspects in the context of the Court Jester model, and an intrinsic lineage attribute. Our results show that this lineage is characterized by a positive near-zero net diversification rate indicating that the clade maintained a relatively low but stable diversity until the Middle Miocene when an increase in extinction rate drove them to decline and eventual extinction. Moreover, our results support the idea that a drastic regional landscape change triggered by the Andean uplift process affected their diversification dynamics, eventually driving them to extinction. These environmental changes could explicitly affect Sparassodonta lineages due to their ever-present vulnerability to extinction by near-zero net diversification rate and their highly specialized ecology that could have constrained adaptation to new South American landscapes. © 2022 Elsevier B.V.
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